Depending on the quality and brand of power supply and what happens when it sees a load of RF coming back down its cable that's definitely a potential issue . .? ?
(50 years experience has taught me that good branded RF proof power supplies are a good use of money.? ?e.g. Pull the top of? a MeanWell professional market 'Mobile radio /base station power 13.6V supply and count the components not in the Chinese look-alike that's a quarter the size and 1/10th the cost)??
I'd fix the QMX, put the BUC supply on the naughty-shelf and see what happens with a decent supply and a well fitting plug . .?
Bruce Akhurst